Trojan:W32/DNSChanger will change the infected system's Domain Name Server (DNS) settings in order to divert traffic to unsolicited, and potentially illegal sites.
Once detected, the F-Secure security product will automatically disinfect the suspect file by either deleting it or renaming it.
More information on the scanning and removal options available in your F-Secure product can be found in the Help Center.
You may also refer to the Knowledge Base on the F-Secure Community site for more assistance.
Trojan:W32/DNSChanger is a family of malware used by an organized crime syndicate to perpetuate click-fraud, where user's browsing activity is quietly manipulated (such as redirecting a user who clicks on a legitimate link to an unsolicited site) so that the attackers can generate revenue from pay-per-click online advertising schemes.
The trojan is usually a small file (about 1.5 kilobytes) that is designed to change the 'NameServer' Registry key value to a custom IP address. This IP address is usually encrypted in the body of a trojan.
As a result of this change, a victim's computer will contact the newly assigned DNS server to resolve names of different webservers.
This malware is discussed further in the following Labs Weblog post:
Lately we got a few samples of this trojan that were named 'PayPal-2.5.200-MSWin32-x86-2005.exe'. This trojan was programmed to change the DNS server name of a victim's computer to 126.96.36.199 address.
The Registry key that is affected by this trojan is:
Other registry modifications made involve creating these keys: